In general, a motorcycle is mounted with an ABS (Antilock Brake System) unit so as to prevent wheels from being locked upon sudden braking. The ABS unit is input with detection signals from a sensor configured to detect a wheel speed and a sensor configured to detect acceleration and the like, and is configured to control brake pressures on front and rear wheels on the basis of the detection signals (for example, refer to Patent Document 1). Since not only the sensor used for the ABS control but also the sensor used to detect a behavior of the vehicle has strict vibration conditions, the sensor is attached to a place of the vehicle to which high-frequency vibrations such as engine vibrations are difficult to be transmitted.
Patent Document 1: Japanese Patent Application Publication No. 2009-292350A
However, an arrangement layout is limited so as to satisfy the vibration conditions of the sensor because the sensor is attached to the place to which the high-frequency vibrations are difficult to be transmitted. For this reason, the sensor may be attached to a place to which an external shock is to be applied upon turnover or collision of the vehicle. Also, when the sensor is attached to the vehicle via a member such as a bracket, the attaching operation is troublesome, maintainability is lowered, and the number of components increases by the bracket, thereby increasing a mounting space.